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Unformatted text preview: quiz 03 GAUTHIER, JOSEPH Due: Nov 14 2007, 10:00 pm 1 Question 1, chap 9, sect 1. part 1 of 1 10 points Given: G = 6 . 673 10 11 N m 2 / kg 2 Two balls, each with a mass of 0.784 kg, exert a gravitational force of 8 . 59 10 11 N on each other. How far apart are the balls? 1. . 649923 m 2. . 670203 m 3. . 691003 m correct 4. . 712451 m 5. . 734539 m 6. . 757284 m 7. . 780962 m 8. . 806763 m Explanation: Basic Concept: F g = G m 1 m 2 r 2 Given: m 1 = m 2 = 0 . 784 kg F g = 8 . 59 10 11 N G = 6 . 673 10 11 N m 2 kg 2 Solution: r 2 = Gm 1 m 2 F g = parenleftBig 6 . 673 10 11 N m 2 kg 2 parenrightBig (0 . 784 kg) 2 8 . 59 10 11 N = 0 . 477485 m 2 Thus r = . 477485 m 2 = 0 . 691003 m Question 2, chap 12, sect 5. part 1 of 2 10 points A wheel is formed from a hoop and four equally spaced spokes. The hoops radius is the length of each spoke. . 099 kg 3 . 6 kg . 26 m There are four equally spaced spokes. Each spoke has mass 0 . 099 kg. The hoops mass is 3 . 6 kg. The hoops radius is 0 . 26 m. Determine the moment of inertia of the wheel about an axis through its center and perpendicular to the plane of the wheel. 1. . 252283 kg m 2 correct 2. . 263865 kg m 2 3. . 27302 kg m 2 4. . 283965 kg m 2 5. . 294298 kg m 2 6. . 30375 kg m 2 7. . 3132 kg m 2 8. . 323331 kg m 2 9. . 334718 kg m 2 10. . 345253 kg m 2 Explanation: Let : n = 4 spokes , m = 0 . 099 kg , M = 3 . 6 kg , and R = 0 . 26 m . Each spoke contributes to the total moment of inertia as a thin rod pivoted at one end, hence I = M R 2 + n mR 2 3 = bracketleftBig M + n m 3 bracketrightBig R 2 = bracketleftbigg (3 . 6 kg) + 4 (0 . 099 kg) 3 bracketrightbigg (0 . 26 m) 2 = 0 . 252283 kg m 2 . quiz 03 GAUTHIER, JOSEPH Due: Nov 14 2007, 10:00 pm 2 Question 3, chap 12, sect 5. part 2 of 2 10 points Determine the moment of inertia of the wheel about an axis through its rim and per pendicular to the plane of the wheel. 1. . 502059 kg m 2 2. . 522413 kg m 2 correct 3. . 548716 kg m 2 4. . 566037 kg m 2 5. . 587059 kg m 2 6. . 611852 kg m 2 7. . 631479 kg m 2 8. . 654545 kg m 2 9. . 676744 kg m 2 10. . 70016 kg m 2 Explanation: From the parallel axis theorem I rim = I + ( M + n m ) R 2 = (0 . 252283 kg m 2 ) + [(3 . 6 kg) + 4 (0 . 099 kg)] (0 . 26 m) 2 = 0 . 522413 kg m 2 . Question 4, chap 10, sect 2. part 1 of 1 10 points Pat builds a track for his model car out of wood. The track is 6 cm wide (along the z coordinate), 1 m high (along the y coordi nate) and 2 . 6 m long (along the x coordinate starting from x = 0). The runway is cut such that it forms part of the lefthand side of a parabola, see figure below. x 1m y 2 . 6 m y = 1 (6 . 76 m) [ x (2 . 6 m)] 2 6 cm Locate the horizontal position of the center of gravity of this track....
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This homework help was uploaded on 03/19/2008 for the course M 408M taught by Professor Gilbert during the Fall '07 term at University of Texas at Austin.
 Fall '07
 Gilbert

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